Dec. 21, 2004: The Associated Press reports on research from the U.S. Geological Service that male smallmouth bass in the Potomac River are discovered to be producing eggs. Endocrine disruption – the biological confusion of an animals’ gender – can be caused by a large number of potential pollutants.

Dec. 21, 2010: The U.S. House of Representatives passed legislation closing loopholes in a U.S. law which allowed shark finning to continue in U.S. waters in the Pacific Ocean. The Senate had passed the bill a day earlier. Up to 73 million sharks are caught each year, their fins removed, and the carcasses dumped back into the ocean to fill the growing demand for shark fin soup, a delicacy in Asia.

Dec. 21, 2011: Following 20 years of furious debate and lobbying, the U.S. E.P.A. sets strict new rules to limit mercury emissions from coal- and oil-burning power plants. The utility industry vows to continue the fight.

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